CON(C)[C:4](=[O:16])[CH2:5][C@H:6]([NH:8][C:9](=[O:15])[O:10][C:11]([CH3:14])([CH3:13])[CH3:12])[CH3:7].[H-].[H-].[H-].[H-].[Li+].[Al+3].C1COCC1>CCOCC>[O:16]=[CH:4][CH2:5][C@H:6]([NH:8][C:9](=[O:15])[O:10][C:11]([CH3:14])([CH3:13])[CH3:12])[CH3:7]To a solution of (R)-tert-butyl 4-(methoxy(methyl)amino)-4-oxobutan-2-ylcarbamate (2.48 g, 10.1 mmol) in Et2O (25 mL) cooled to −5° C. was added dropwise a 2.0 M solution of LAH in THF (6.28 mL, 12.6 mmol). After the addition, the resulting slightly milky solution was stirred at 0° C. for 1.5 hr. The reaction mixture was quenched with 1 M aqueous KHSO4 (20 mL) and diluted with water (30 mL). The resulting solution with white milky precipitate was extracted with Et2O (3×). The combined Et2O extracts were washed with 0.5 M aqueous KHSO4 (2×20 mL), saturated aqueous NaHCO3, water, and saturated aqueous NaCl, dried over Na2SO4, filtered and concentrated. The residue was dried under vacuum to give (R)-tert-butyl 4-oxobutan-2-ylcarbamate (1.57 g, 8.40 mmol, 84% yield) as a colorless oil. 1H NMR (400 MHz, CDCl3) δ ppm 9.76 (s, 1H), 4.64 (s, 1H), 4.20-4.08 (m, 1H), 2.69-2.52 (m, 2H), 1.43 (s, 9H), 1.24 (d, J=6.8 Hz, 3H).
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